This invention relates to d.c. electric motors for automotive applications and, more particularly, to a choke having features for improved mechanical and electrical connection with components of a brush card assembly.
Typical multi-pole automotive d.c. electric motors use bus bars to conduct current between the electrical connector of the motor and associated components such as chokes, capacitors, and brushes. Conventional bus bars have to be manufactured and physically attached, supported and connected with the motor. Typically, the bus bars are riveted to the brush card of the motor. The electrical connection is usually achieved using soldered or heat-fused joints.
Thus, there is a need to reduce the number of electrical connections required on the motor""s brush card, to eliminate costly bus bars and to reduce the number of separate mechanical fasteners needed on the brush card.
Furthermore, conventionally, wound wire coils or chokes are installed close to the brushes of d.c. motors, particularly in automotive applications. The purpose of the chokes is to suppress radio-frequency interference (RFI) generated by the motor. Generally, the chokes are physically attached to the brush card of the motor using fixing or fastening techniques that require additional specific parts or processes, for example, the ends of the chokes may be soldered to conductors that are riveted to the brush card, the chokes may be installed within purpose-designed locations molded into the brush card, and/or clips or other fasteners may be used to attached the chokes.
Hence, there is also a need to provide secure mechanical attachment of the choke to the brush card while avoiding the necessity of either a molded brush card or specific fastening components.
An object of the present invention is to fulfill the needs referred to above. In accordance with the principles of the present invention, this objective is obtained by providing a choke for suppressing radio-frequency interference of a brush-type motor. The choke includes a single wire having a portion wound about a coil axis to define a plurality of coils including two outermost coils. An attaching structure extends from each outermost coil and is disposed generally transverse with respect to the coil axis. Each attaching structure is constructed and arranged to be inserted through an associated opening in a supporting structure and to be bent so as secure the choke to the supporting structure. An elongated end portion extends from each attaching structure so as to be spaced from and generally parallel to the coil axis. The elongated end portions extend in opposite directions. One of the elongated end portions is constructed and arranged to be directly electrically connected to an electrical connector of a motor and the other of the elongated end portions is constructed and arranged to be in electrical connection with a brush of the motor.
In accordance with another aspect of the invention, a brush card assembly for a d.c. motor includes at least one choke having a portion wound about a coil axis to define a plurality of coils including two outermost coils, an attaching structure extending from each outermost coil and being generally transverse with respect to the coil axis. An elongated end portion extends from each attaching structure so as to be spaced from and generally parallel to the coil axis, the elongated end portions extending in opposite directions. The assembly further includes a brush card having first and second opposing sides and a pair of openings through the opposing sides. Each attaching structure is disposed through an associated opening and bent so as to be adjacent to the second side, with the wound portion of the choke being disposed on the first side of the brush card, such that the choke is secured to the brush card. A brush is mounted on the brush card and is in electrical connection with one of the elongated end portions. An electrical connector is mounted on the brush card. The electrical connector has a terminal receiving the other elongated end portion of the choke.
In accordance with yet another aspect of the invention, a method of connecting a choke to a brush card assembly is provided. The choke include a portion wound about a coil axis to define a plurality of coils including two outermost coils. An attaching structure extends from each outermost coil and is disposed generally transverse with respect to the coil axis. An elongated end portion extends from each attaching structure so as to be spaced from and generally parallel to the coil axis. The elongated end portions extend in opposite directions. The brush card assembly includes a brush card having first and second opposing sides and a pair of openings through the opposing sides. A brush and an electrical connector are mounted on the brush card. The electrical connector has a terminal. The method includes the steps of inserting each attaching structure through an associated opening, with the wound portion of the choke being disposed on the first side of the brush card, bending each attaching structure so as to be adjacent to the second side, thereby securing the choke to the brush card, directly electrically connecting one of the elongated end portions with the terminal, and electrically connecting the other elongated end portion with the brush.
Other objects, features and characteristics of the present invention, as well as the methods of operation and the functions of the related elements of the structure, the combination of parts and economics of manufacture will become more apparent upon consideration of the following detailed description and appended claims with reference to the accompanying drawings, all of which form a part of this specification.